agent: Replace some sprintf.
* agent/call-scd.c (agent_card_pksign): Replace sprintf by bin2hex. * agent/command-ssh.c (ssh_identity_register): Ditto. * agent/pkdecrypt.c (agent_pkdecrypt): Replace sprintf by put_membuf_printf.
- Signed-off-by: Werner Koch <wk@gnupg.org>